Manganous dimethyldithiocarbamate stabilized with zinc dimethyldithiocarbamate



MANGANOUS DIMETHYLDITHIOCARBAMATE STABTLIZED WITH ZINC DI METHYLDITHIO-CAAMATE No Drawing. Application April 5, 1957 Serial No. 650,826

7 Claims. (Cl. 260-429) This invention relates to mixtures of manganousand zinc dimethyldithiocarbamates in which the manganousdimethyldithiocarbamate is stabilized against spontaneous combustion anddeterioration and to processes for preparing such stabilized mixtures.

The fungicidal properties of manganous dimethyldithiocarbamate are knownto the art and the inherent instability of manganousdimethyldithiocarbamate has been recognized as in the U. S. Patent toFlenner No. 2,504,404. Johnson Patent No. 2,665,285 describes thestabilization of manganous dimethyldithiocarbamate by the use of anadded stabilizer such as suitable sulfites.

The value of manganous dimethyldithiocarbamate as a fungicide and itsinherent instability are also recognized in the Bradley PatentNo.-2,765,327 where Bradley proposes to remove the inherent instabilityof the manganous dimethyldithiocarbamate by washing a precipiie StatesPatent() tate thereof in the absence of air to remove water soluble Vsalts. I

It is therefore well established that manganous dimethyldithiocarbamateis effective as a fungicide but is impractical and inherently hazardousbecause itis subject to spontaneous combustion and to deterioration onstorage Most unexpectedly we have found that intimate mixtures ofmanganous dimethyldithiocarbamate with substantial amounts of zincdimethyldithiocarbamate stabilize the manganousdimethyldithiocarbamate"against spontaneous combustion and deteriorationwithout deleterious effects on its fungicidal activity., We have furtherfound that such mixtures can be driedsafely and stored at elevatedtemperatures without the he hazards involved in present manufacture,storage and use of manganous dimethyldithiocarbamate;

It is therefore an object of the present invention to provide mixturesof manganous and zinc dimethyldithiocarbamates which are stable and inwhich the manganous,

dimethyldithiocarbamate is not subject to spontaneous combustion or todeteriorati on, such mixtures havingno,

deleterious effectson the fungicidal activity of the man-. ganousdimethyldithiocarbamate.

Another object of the preselit invention is to provide novel processesfor obtaining intimate mixtures of manganous and zincdirnethyldithiocarbamates in which substantial amounts of zincdimethyldithiocarbamate are present.

Other and further objects of the present invention will appear from thefollowing description of illustrative embodiments thereof.

The procedures of the present invention and the prod ucts thereof arecapable of various modifications within the scope of the presentinventive concept and reference should therefore be had to the appendedclaims to determine the scope of this invention.

As noted above, varying amounts of zinc dimethyldithiocarbamate may bemixed with the manganous dimethyldithiocarbamate to stabilize themanganous dimethyldithiocarbamate against spontaneous combustion anddeterioration. Mixtures containing less-hthan'-; 50:%Y

zinc dimethyldithiocarbamate may come within the present concept andmixtures containing at least about 50%, of zinc dimethyldithiocarbamatehave been found tomeet; the objectives of the present invention, Suchmixtures of manganous and zinc dimethyldithiocarbamates can be dried andstored safely at elevated temperatures without 1 deleterious effects onfungicidal activity and without il'l6'-;

known hazards of spontaneous combustion inherent-in the handling ofmanganous dimethyldithiocarbamate. Mixtures of manganous and zincdimethyldithiocar-,;- bamates can be prepared in various ways as byintimately dry-mixing the two salts in any suitable manner. Since suchdry-mixing of the two salts entails drying;unstabilized manganousdimethyldithiocarbamate before mix- 1 ing with its inherent diflicultiesmentioned above; how ever, we prefer to prepare the stabilized mixtureofman-; ganous and zinc dimethyldithiocarbamates by co-precipia-v tationof manganousdimethyldithiocarbamate and"zinc..;. dimethyldithiocarbamateby processes utilizing thereaction in aqueous solution of desired ratiosof inorganic water-soluble manganous and zinc salts with an alkali metalor alkaline earth metal dimethyldithiocarbamate;' The resultingprecipitate is an intimate, stable mixture of manganous and zincdimethyldithiocarbamates which remains stable upon drying and storing. I

A stable mixture of manganous and zinc dimethyldithiocarbamate's isobtained in the process generally. del scribed above when the ratio ofzinc to manganous saltsv is such as to give substantial amounts of zincdimethyldithiocarbamate in the mixture and may be at ,least-= about oneto one. a

The precipitate of such a process may be dried. conventional methodsutilizing tray-drying at 140 F. or flash-drying at 190 F. withoutcombustion or darkening comparable to that of the manganese salt aloneof'the precipitate. These precipitates have beenstored in'bulk forextended periods at temperatures up to 135 and striking differences wereobtained in'the'dryijngand storage properties of the manganousdimethyldithiocarbamate. Manganous dimethyldithiocarbamate I alone' whentray-dried at 120 F. darkened appreciably and ignited spontaneously whenstored in bulk at 120? Mixtures of manganous and zinc;dimethyldithiocarbamates of the present invention have exhibited no loss'in fungicidal activity when'subjected to storage 'in bulk at elevatedtemperatures as high as 135 FffThe fu'ng toxicity of these mixtures whenstored'in bulk "at elevated temperatures for long periods of time wasdetermined by As noted above the procedures of the present invention andthe products thereof are capable of various modifications all within thescope of the present inventive concept. In a typical process resultingin a stabilized mixture of manganous and zinc dimethyldithiocarbamateshaving stability against spontaneous com bustion and the ability toremain in storage for long periods of time at high temperatures withoutloss of fungitoxicity, 350 pounds of a 7.16% aqueous solution of sodiumhydroxide at about F. was employed to which was added 70.5 pounds of a40% aqueous solution of dimethylamine and the mixed solutions wereagitated. A total of fifty pounds of carbon bisulfide was then addedslowly with agitation over a period of about 30 to 35 minutesmaintaining the temperature of the solution below F. A solution ofsodium dimethyldithiocarbamate was formed having a pH of 8.5-9.0. T9

Patented Nov. 18,1958- this solution ofsodium dimethyldithiocarbamate181 pounds ofa solution containing 24.88 pounds of MnSO, and 25.48pounds of ZnSO were added rapidly with agitation. A mixture of manganousand zinc dimethyldithioearbamatesprecipitated in this solution and wasremoved by filtration'on a plate 'and frame filter press. The filteredmixture was washed with water and traydried in anoven at 135 F. Thedried material was then pulverized and was of a light tan to greencolor. Fifty pounds of the tray-dried material was then stored in afiber drum at 13ll33 F. for 29 days without evidence of decomposition orloss of fungitoxicity.

In another example of a process and product in accordance with thepresent invention, 350 pounds of 7.16% aqueous solution of sodiumhydroxide at about 75 F. was employed to which was added 70.5 pounds ofa 40% aqueous solution of dirnethylamine with agitation. Fifty pounds ofcarbon bisulfide was then; added slowly with agitation to this solutionover a period of about 30 to 35' minutes maintaining the temperaturebelow 85 F. A solution of sodium dimethyldithiocarbamate was formedhaving a pH of 8.5 to 9.0. To this solution ofi'sodiumdimethyldithioearbamate was then added rapidly w-ith agitation 198.5pounds of; a solution containing 14.95- pounds of MnSO and 34.86 poundsof'ZnSO A mixture of manganous and zinc dimethyldithiocarbamatesprecipitated and was removed by filtration on; a plate and frame filter'press, the mixture was washed with water, was tray-dried at 1 35"-'.F., and the dried material was pulverized and was of a light tan togreen color. Fifty'pounds of the tray-dried material was then stored ina'fib'er drum at 135- F.'f orfourteen days without evidence ordecomposition or loss of fungitoxicity.

The dithiocarbamate mixture containing 70% Zn salt gave the followingpercentage spore germination of M onilinia fructicola (M) andCurvularz'a lunata (C) before andafter' storage at 135 F. for 14 days:

etor M: 32 p. p.'m., 29%; 63. pap. m., 0% C: 63p. p. 111., 99%; 125 p.p. m, 2% After-..

I M; 32 p. p. m., 13%; 63 p. p. m., 0%

C: 63 p. p.'m 91%; .,25fpfp. 1:1,, 0%

The dithiocarbamate mixture containing 50% zinc salt gave the followingpercentage spore germination of Carvularia lunata (C) before and afterstorage at 131-133 F. for twenty-nine days: 1

fore-C: .6.1 n 6. 32 pp 3%; 6

.,;'0% A ter'C= 35 pm- 2 pp.

carbamates stabilized against spontaneous combustionand. deteriorationhave been obtained when the percentage of zinc Salts present was atleast about 50% but lesser 4 amounts of the zinc salts will secure thedesired stabilization of the manganous dimethyldithiocarbamate dependingupon the conditions under which the co-precipitated mixtures ofmanganous and zinc dimethyldithiocarbamates are obtained or used.

It should now be apparent to those skilled in the art that the presentinvention in every way satisfies the several objectives discussed above.

Changes in the above described illustrative procedures and in thecomposition of the mixtures of manganous and Zincdimethyldithiocarbamates may now be suggested to those skilled in theart Without departing from the present inventive concept. Referenceshould therefore be had to the appended claims; to determine the scopeof this invention.

What is claimed is:

l. A co-precipitated intimates mixture of manganous and zincdimethyldithiocarbamates containing from about 50% to zincdimethyldithiocarbamate having stability against spontaneous combustion,deterioration, and loss of fungitoxicity.

2. A mixture of Zinc and manganous dimethyldithiocarbamates containingfrom about 50% to 70% zinc dimethyldithiocarbamate having stabilityagainst spontaneous combustion, deterioration, and loss offungitoxicity.

3. In a process for stabilizing manganous dimethyldithiocarbamateagainst spontaneous combustion, deterioration, and loss offungitoxicity, the steps of mixing an aqueous solution of inorganicsoluble manganous and zinc salts and an aqueous solution of a chemicalcompound selected from the group consisting of alkali metaldimethyldithiocarbam'ates and alkaline earth dimethyldithiocarbamatesuntil a slurry is obtained, filtering the slurry to remove precipitatedmanganous and Zinc dimethyldithiocarbamates, washing the precipitatedmanganous and zinc dimethyldithiocarb'amates with water, and then dryingthe manganous and zinc dimethyldithiocarbamatcs.

4. A process as described in claim 3 in which the organic water-solublesalts are manganoussulfate and zinc sulfate.

5. A process as described in claim 3 in which the solubledimethyldithiocarbamate is sodium dimethyldithiocarbamate.

6. A process as described in claim 3, in which the manganous and zincdimethyldithiocarbamates are traydried at approximately 135-l40 F.

7. A process as described in claim 3 in which the manganous and zincdimethyldithiocarbamates are flash-dried at approximately 1 F.

References Cited inthe file of this patent UNITED STATES PATENTS2,406,960 Neal et al Sept. 3, 1946 2,504,404 Flenner Apr. 18, 19502,665,285 Johnson Jan. 5, 1954 2,765,254 Somerville Oct. 2, 1956

1. A CO-PRECIPITATED INTIMATES MIXTURES OF MANGANOUS AND ZINCDIMETHYLDITHIOCARBOMATES CONTAINING FROM ABOUT 50% TO 70% ZINCDIMETHYLDITHIOCARBAMATE HAVING STABILITY AGAINST SPONTANEOUS COMBUSION,DETERIORATION, AND LOSS OF FUNGITOXICITY.
 3. IN A PROCESS FORSTABILIZING MANGANOUS DIMETHYLDITHIOCARBONAMATE AGAINST SPONTANEOUSCOMBUSTION, DETERIORATION, AND LOSS OF FUNGITOXICITY, THE STEPS OFMIXING AN AQUEOUS SOLUTION OF INORGANIC SOLUBLE MANGANOUS AND ZINC SALTSAND AN AQUEOUS SOLUTION OF A CHEMICAL COMPOUND SELECTED FROM THE GROUPCONSISTING OF ALKALI METAL DIMETHYLDITHIOCARBAMATES AND ALKALINE EARTHDIMETHYLDITHIOCARBAMATES UNTIL A SLURRY IS OBTAINED, FILTERING THESLURRY TO REMOVE PRECIPITATED MANGANOUS AND ZINCDIMETHYLDITHIOCARBAMATES, WASHING THE PRECIPITATED MANGANOUS AND ZINCDIMETHYLDITHIOCARBAMATES WITH WATER, AND THEN DRYING THE MANGANOUS ANDZINC DIMETHYLDITHIOCARBAMATES.